cPanel

in order to link the website to Cloudflare and keep the emails working we need to add these DNSs into the Cloudfalre

First record : 

Recrord Type = A

Name = mail

Content = {Cpanel Server IP}

Second Record 

Recrord Type = MX

Name = example.com

Content = mail.example.com

in this case your email from webemail will be working as expected